Differential with cross pin retention system and method for assembly

ABSTRACT

A differential assembly includes a retainer for a cross pin having a bore aligned with a bore formed in a differential housing. The cross pin retainer is positionable at partially-inserted and fully-inserted positions within the cross pin and differential bores. At a first rotational orientation, the cross pin retainer is positionable in its partially-inserted position to temporarily retain the cross pin within the differential housing. At a second rotational orientation, the cross pin retainer is positionable in its fully-inserted position to retain the cross pin within the differential housing. Features of the cross pin retainer cooperate with surfaces formed in the differential housing to allow the cross pin retainer to be fixedly positioned and secured within the differential housing.

FIELD

The present disclosure relates generally to differentials for use inautomotive drivelines and, more particularly, to a method and anapparatus for retaining a cross pin within a differential housing.

BACKGROUND

The statements in this section merely provide background informationrelated to the present disclosure and may not constitute prior art.

Many automotive drive axle assemblies include a hypoid gearset and adifferential for changing the direction of power transmission from anaxis parallel to the direction of vehicle travel to an axisperpendicular thereto. The hypoid gearset typically includes a ring gearcoupled to a differential housing which is meshed with a pinion gearrotatably supported within the axle housing. To facilitate properfunction of the drive axle assembly, the differential is rotatablymounted on a pair of differential bearings. The differential in mostautomotive drive axle assemblies includes a gearset which is supportedwithin the differential housing to facilitate relative rotation betweena pair of axle shafts. The differential gearset typically includes apair of side gears that are coupled to the ends of axle shafts. The sidegears are meshed with at least one set of pinions rotatably supported ona cross pin that is coupled to the differential housing.

Various methods are known for securing the cross pin to the differentialhousing. For example, at least one known differential uses a threadedfastener, such as a lock screw or bolt, to secure the cross pin to thedifferential housing. The threaded fastener extends through an aperturein the differential cross pin and is threadingly engaged with a hole inthe differential housing. As an alternative, a roll-pin may be insertedbetween aligned holes in the differential housing and the cross pin toprovide a non-threaded retention mechanism. Another known method ofsecuring the differential cross pin includes positioning a snap ringwithin a groove formed in the cross pin and a corresponding grooveformed in the differential housing.

The above-noted cross pin retention mechanisms may require costlymachining operations to be performed on the differential housing, thecross pin or both. Furthermore, a costly and time-consuming torquingoperation may be required when using a threaded fastener. Additionally,these retention methods may not permit convenient removal of the crosspin during assembly of the differential or axle assembly. Elimination ofthe torquing process or lock ring assembly steps may also be beneficialin reducing the time and cost required to manufacture the differential.In addition, the ability to conveniently remove the cross pin during theassembly process may be beneficial to reduce the time and cost requiredto interconnect the axle shafts to the side gears of the differential.

SUMMARY

The present disclosure provides an arrangement for securely retainingthe cross pin within the housing of a differential assembly. Theimproved arrangement for retaining the cross pin includes the use of across pin retainer which permits relatively simple and rapid assembly ofthe differential assembly. The cross pin retainer is positionable at afirst or partially-inserted position to temporarily retain the cross pinwithin the differential housing and to permit easy removal of the crosspin retainer and cross pin during assembly of the axle assembly. Whenlocated in its partially-inserted position, a portion of the cross pinretainer elastically deforms and snugly engages a retention bore formedin the differential housing.

The cross pin retainer is also positionable at a second orfully-inserted position to permit retention of the cross pin within thedifferential housing. When located in its fully-inserted position, aportion of the cross pin retainer expands to engage a wall in thedifferential housing to restrict subsequent retraction of the cross pinretainer. Additionally, the cross pin retainer and the differentialhousing include surfaces that cooperate to facilitate the partial andfull insertion of the cross pin retainer into the differential assembly.

The present disclosure eliminates the need for costly machiningoperations previously required to provide an annular grove orthroughbore in the differential housing. The present disclosure alsoprovides for increased case strength by permitting use of smaller boresizes in the differential housing. Finally, the present disclosureprovides a method which may reduce the cost of a differential assemblyby providing simpler manufacturing methods. Accordingly, costs arefurther minimized by reducing the time required to assemble thedifferential assembly and install the various components of an axleassembly.

Further areas of applicability will become apparent from the descriptionprovided herein. It should be understood that the description andspecific examples are intended for purposes of illustration only and arenot intended to limit the scope of the present disclosure.

DRAWINGS

The present disclosure will become more fully understood from thedetailed description and the accompanying drawings. The drawingsdescribed herein are for illustration purposes only and are not intendedto limit the scope of the present disclosure in any way.

FIG. 1 is an exploded perspective view of an exemplary drive axleassembly equipped with a differential assembly having a cross pinretention system according to the present disclosure;

FIG. 2 is an exploded perspective view of the differential assemblyhaving a cross pin retention system according to the present disclosure;

FIG. 3 is an end view of the differential housing shown in FIG. 2;

FIG. 4 is a sectional view of the differential housing shown in FIG. 3;

FIG. 5 is an end view of the cross pin retainer shown in FIG. 1;

FIG. 6 is a fragmentary sectional side view of the differential assemblyshown in FIG. 4;

FIG. 7 is a fragmentary sectional top view of the differential assemblyshown in FIG. 4;

FIG. 8 is a fragmentary sectional side view of the differential assemblyshown in FIG. 4 having the cross pin retainer located in apartially-inserted position;

FIG. 9 is a fragmentary sectional top view of the differential assemblyshown in FIG. 4 having the cross pin retainer located in apartially-inserted position;

FIG. 10 is a fragmentary sectional side view of another differentialassembly;

FIG. 11 is a fragmentary sectional top view of the differential assemblyshown in FIG. 10 having the cross pin retainer located in afully-inserted position;

FIG. 12 is a fragmentary sectional side view of the differentialassembly shown in FIG. 10 having the cross pin retainer located in apartially-inserted position;

FIG. 13 is a fragmentary sectional top view of the differential assemblyshown in FIG. 10 having the cross pin retainer located in apartially-inserted position;

FIG. 14 is an end view of another cross pin retainer according to thepresent disclosure;

FIG. 15 is a sectional side view of the cross pin retainer shown in FIG.14;

FIG. 16 is an end view of yet another cross pin retainer according tothe present disclosure; and

FIG. 17 is a sectional side view of the cross pin retainer shown in FIG.16.

DETAILED DESCRIPTION

The following description is merely exemplary in nature and is in no wayintended to limit the invention, its application, or uses.

With reference to FIGS. 1 and 2, a cross pin retention system isgenerally identified by reference numeral 10. Cross pin retention system10 is shown operatively associated with an exemplary drive axle assembly12. Drive axle assembly 12 includes an axle housing 14 for rotatablysupporting a hypoid gearset including a pinion gear 16 and a ring gear18 which is secured to a differential assembly 20. Differential assembly20 functions to transfer power from pinion gear 16 to a pair of axleshafts 22 and 23 while compensating for any difference in axle shaftrotary speeds as may occur during a turn or other steering maneuver.

In order to compensate for differences in the axle shaft rotary speeds,differential assembly 20 includes a pair of pinion gears 24 and a pairof side gears 26 which are drivingly interconnected to axle shafts 22and 23. To facilitate proper function of axle assembly 12, differentialassembly 20 is rotatably mounted in axle housing 14 by a pair ofdifferential bearings 28. More particularly, housing 14 includes twosemi-circular journals (not shown) for supporting approximately one-halfof the circumferences of each differential bearing 28. A pair of bearingcaps 30 generally supports the remaining approximate one-half of eachdifferential bearing 28. Each bearing cap 30 is mounted to axle housing14 in a manner conventional in the art such as via threaded fasteners.

Referring primarily to FIGS. 2 through 4, differential assembly 20includes a differential case or housing 32, a cross pin 34, a pair ofside gear washers 36 and a pair of pinion gear washers 38 in addition topinion gears 24 and side gears 26 previously introduced. Differentialhousing 32 includes an interior cavity 40 defined by a wall 42.Differential housing 32 includes a pair of axially aligned openings 44extending through wall 42 and which interconnect interior cavity 40 withan external surface 46 of differential housing 32. Openings 44 are sizedto rotatably support side gears 26. Openings 44 also allow axle shafts22 and 23 to be inserted within interior cavity 40 and engage internalsplines 48 on side gears 26.

Differential housing 32 also includes a first aperture 50 and a secondaperture 52 that are axially aligned with one another. Each of first andsecond apertures 50 and 52 extends through wall 42 to interconnectinterior cavity 40 with external surface 46 of differential housing 32.A first housing bore 56 extends through wall 42 from external surface 46to intersect first aperture 50. A second housing bore 60 extends throughwall 42 from external surface 46 to intersect second aperture 52.

Cross pin 34 is a generally cylindrically-shaped member having a firstend 62 and a second end 64. First end 62 includes a first cross pin bore66 while second end 64 includes a second cross pin bore 68. A pair offlats 70 (FIG. 2) are formed on cross pin 34 to function as lubricantreservoirs during operation. Cross pin 34 is positioned within first andsecond apertures 50 and 52 such that first cross pin bore 66 is alignedwith first housing bore 56. Likewise, second end 64 of cross pin 34 ispositioned within second aperture 52 to align second cross pin bore 68with second housing bore 60.

Pinion gears 24 are rotatably supported on cross pin 34. Pinion gearwashers 38 are positioned within interior cavity 40 between wall 42 andpinion gears 24. Each pinion gear washers 38 provides a thrust surfaceagainst which the pinion gears may bear. Similarly, side gear washers 36are positioned between side gears 26 and differential housing 32.

Referring now primarily to FIGS. 5 through 9, cross pin 34 is shown tobe retained within differential housing 32 by a cross pin retainer 100.As best seen in FIG. 6, cross pin retainer 100 is positioned withinaligned bores 56 and 66. Although a single cross pin retainer 100 isshown, it should be appreciated that a second cross pin retainer 100 maybe positioned in aligned bores 60 and 68 to provide additional retentionof cross pin 34. Cross pin retainer 100 is formed of a semi-compliantmaterial (i.e., a polymer, nylon, plastic, etc.) having substantiallylower mechanical properties than differential assembly 32 and cross pin34.

As best seen in FIGS. 6 through 9, cross pin retainer 100 has a body102, a first end 104 and a second end 106. Body 102 iscylindrically-shaped and adapted to support cross pin retainer 100within differential housing bore 56. First end 104 may be rectangular inshape and has a pair of opposing face surfaces 108 and 110 and an indexsurface 112. Opposing face surfaces 108 and 110 are adapted to allowcross pin retainer 100 to be grasped and positioned. Index surface 112is adapted to engage a first wall surface 114 of differential housing 32when cross pin retainer 100 is positioned in its partially-insertedposition at a first rotational orientation, as shown in FIG. 8. Indexsurface 112 is also adapted to engage a second wall surface 116 ofdifferential housing 32 when cross pin retainer 100 is positioned in itsfully-inserted position at a second rotational orientation, as shown inFIG. 11. Second end 106 is generally conically-shaped to facilitate theinsertion of cross pin retainer 100 within housing bore 56 and includesa slot 118 and a retention surface 120.

As best seen from FIG. 5, second end 106 may have, but not limited to,an elliptical base with a minor diameter 124 and a major diameter 126.Minor diameter 124 is substantially equal to the diameter ofdifferential housing bore 56 and is adapted to allow cross pin retainer100 to be inserted within housing bore 56. Major diameter 126 is greaterthan the diameter of bore 56 to permit retention of cross pin retainer100 within differential housing 32 when located in its fully-insertedposition. Slot 118 is oriented perpendicular to the axis of majordiameter 126 and extends from second end 106 partially into body 102.Slot 118 is dimensioned such that second end 106 may be sufficientlycompressed (see FIG. 9) to allow second end 106 to be positioned withindifferential housing bore 56. Retention surface 120 is adapted to engagea wall 122 defining first aperture 50 when cross pin retainer 100 islocated in its full-inserted position.

As previously stated, cross pin retainer 100 may be positioned at afully-inserted position and at a partially-inserted position to retaincross pin 34. It may be particularly desirable to locate cross pinretainer 100 at the partially-inserted position to permit partialextraction of cross pin retainer 100 and subsequent removal of cross pin34 during the assembly of drive axle assembly 12. Accordingly, cross pinretainer 100 may be positioned within housing bore 56 at itspartially-inserted position by grasping and positioning first end 104 atthe first rotational position with respect to differential housing 32,inserting second end 106 within differential housing bore 56 andtranslating cross pin retainer 100 toward first aperture 50 until indexsurface 112 engages first wall surface 114 of differential housing 32.When cross pin retainer 100 is located in its partially-insertedposition, a portion of second end 106 extends into aperture 50 toprovide retention of cross pin 34, yet cross pin retainer 100 may beeasily retracted from housing bore 56.

Cross pin retainer 100 may then be positioned within housing bore 56 toa fully-inserted position by grasping and rotating first end 104 to itssecond rotational position with respect to differential housing 32 andfurther translating cross pin retainer 100 toward first aperture 50until index surface 112 engages second wall surface 116 of differentialhousing 32. When cross pin retainer 100 is in its fully-insertedposition, second end 106 is positioned within aperture 50 such thatretention surface 120 engages wall 122 formed by aperture 50, therebysecuring cross pin retainer 100 within differential housing 32.Additionally, first end 104 is positioned within a channel (see FIG. 3)having a bottom formed by second wall surface 116 and sides formed by awall 128. Wall 128 provides a clearance between first end 104 anddifferential housing 32 at the second rotational orientation, butsubstantially limits rotation of first end 104 when cross pin retainer100 is located in its fully-inserted position. Should it be desired, asecond cross pin retainer 100 may be positioned within bores 60 and 68in a manner similar to that just described.

It should be appreciated that differential assembly 20 is serviceableshould the need arise. Because cross pin retainer 100 exhibitssubstantially lower mechanical properties than cross pin 34 ordifferential housing 32, differential assembly 20 may be disassembled byshearing cross pin retainer 100 by driving cross pin 34 along itslongitudinal axis. Once disassembled, differential assembly 20 may beserviced and reassembled by positioning either one or two new cross pinretainers 100 within differential housing 32 in the manner previouslydescribed. Removal of cross pin retainer 100 may also be facilitated byheating differential housing 32 and cross pin 34 to a sufficienttemperature to cause cross pin 100 to melt and then driving cross pin 34along its longitudinal axis.

With reference now to FIGS. 10 through 13, another cross pin retentionsystem in accordance with the present disclosure will be more fullydescribed. A cross pin retainer 200 includes a retention member 202 inslidable receipt of a support pin 204, a first end 206, and a second end208. Retention member 202 includes a body 210 having a throughbore 212in receipt of pin 204. Bore 212 is coaxially aligned with body 210 andextends through first end 206 and body 210 to permit the insertion ofsupport pin 204 into body 210. Support pin 204 has a shaft 216 and ahead 218. Shaft 216 is cylindrical and is adapted to fit snugly in bore212. Head 218 is larger than bore 212 and has a face surface 220 adaptedto engage a face surface 222 of first end 206 when support pin 204 ispositioned at a fully-inserted position. Preferably, support pin 204 isformed of a material with mechanical properties greater than those ofretention member 202, but substantially lower than differential housing32.

Cross pin retainer 200 may be positioned at a partially-insertedposition as shown in FIGS. 12 and 13, as well as at a fully-insertedposition as shown in FIGS. 10 and 11. Retention member 202 includes agraspable tab 224 shaped similarly to first end 104 of cross pinretainer 100. Tab 224 operates in a manner substantially similar tofirst end 104, as previously described for cross pin retainer 100.Support pin 204 is moveable between a first position shown in FIGS. 12and 13 and a second position shown in FIGS. 10 and 11. Support pin 204is located in its first position during location of cross pin retainer200 in its partially-inserted position.

To place cross pin retainer 200 in the fully-inserted position,retention member 202 is displaced toward the fully-inserted positionwhile support pin 204 remains in its first position. Second end 208 isallowed to collapse a slot 226 formed in retention member 202. Oncesecond end 208 enters bore 50, body 210 returns to its undeformed shapeand a retention surface 228 engages wall surface 122. At this time, anoperator axially displaces support pin 204 from the first position tothe second position. Support pin 204 is translated through throughbore212 and aperture 50 until face surface 220 is seatingly engaged withface surface 222. When fully seated, support pin 204 is positionedwithin a blind bore 230 in differential housing 32. Blind bore 230 isadapted to receive support pin 204. In this manner, support pin 204provides additional structural support for cross pin 34 and retentionmember 202.

It should be appreciated that support pin 204 may have a shaft which isshorter than shown and which may extend through body 210 to second end208, but does not extend into blind bore 230. It should also beappreciated that support pin 204 may be molded into retention member 202to form a composite cross pin retainer according the teachings of thepresent disclosure. Finally, it should also be appreciated that supportpin 204 may be subassembled to retention member 202 to facilitate thepartial and full insertion of cross pin retainer 200 in differentialhousing 32.

While two cross pin retainers in accordance with the present retentionmechanism have been fully described, other embodiments of the cross pinretainer of the present disclosure, such as those illustrated in FIGS.14 through 17, will now be described. Referring to FIGS. 14 and 15, across pin retainer 300 comprises a retention member 302 and a supportpin 304. Support pin 304 is substantially similar to support pin 204 ofcross pin retainer 200. Retention member 302 further comprises a body306, a first end 308 and a second end 310. First end 308 and second end310 are substantially similar to first end 206 and second end 208 ofcross pin retainer 200. Body 306 includes annular fins 312 that areadapted to elastically deform as cross pin retainer 300 is positioned inbore 56 to a partially-inserted position as previously described. Tothis end, body 306 has a minor diameter 314 that is sufficiently smallerthan the diameter of bore 56 to allow annular fins 312 to elasticallydeform while positioned within bore 56. Annular fins 312 include aretention surface 316 which is adapted to engage wall 122 of aperture 50when cross pin retainer 300 is positioned in its fully-insertedposition, as previously described. Once annular fins 312 are positionedwithin aperture 50, annular fins 312 expand to cause retention surface316 to engage wall surface 122.

Referring to FIGS. 16 and 17, a cross pin retainer 400 is shown toinclude retention member 402 and a support pin 404. Support pin 404 issubstantially similar to support pin 204 of cross pin retainer 200.Retention member 402 further comprises a body 406, a first end 408 and asecond end 410. First end 408 is substantially similar to first end 206of cross pin retainer 200. Cross pin retainer 400 further comprises anaperture 412 extending through body 406 and second end 410. Aperture 412is sized to allow a portion of body 406 and second end 410 toelastically deform as cross pin retainer 400 is positioned in bore 56 toa partially-inserted position as previously described. To this end,aperture 412 has a height 414 that is sufficient to allow a portion ofbody 406 and second end 410 to elastically deform while positionedwithin bore 56. Second end 410 includes a retention surface 416 whichengages wall surface 122 of aperture 50 when cross pin retainer 400 ispositioned in its fully-inserted position as previously described.

The foregoing discussion discloses and describes merely exemplaryembodiments of the present invention. One skilled in the art willreadily recognize from such discussion, and from the accompanyingdrawings and claims, that various other changes, modifications andvariations may be made therein without department from the spirit andscope of the invention as defined in the following claims.

1. A differential gear assembly, comprising: a differential housingadapted to be rotatably supported within an axle housing, saiddifferential housing having an interior chamber, a first aperture and asecond aperture, said first and second apertures being axially alignedwith each other, said differential housing having a bore extending intosaid first aperture; side gears rotatably supported within said interiorchamber of said differential housing; a cross pin supported in saidinterior chamber of said differential housing, said cross pin havingends positioned within said first and second apertures, said cross pinhaving a transversely extending bore aligned with said bore in saiddifferential housing; pinion gears rotatably supported on said cross pinand in meshed engagement with said side gears; and a cross pin retainerselectively positionable at a partially-inserted position and at afully-inserted position with respect to said differential housing, saidcross pin retainer including a first end rotatable between first andsecond rotational orientations, said first end restricting axialmovement of said cross pin retainer to said fully-inserted position andallowing axial movement to said partially-inserted position when locatedin its first rotational orientation, said first end allowing axialmovement of said cross pin retainer to said fully-inserted position whenlocated in its second rotational orientation.
 2. The differential gearassembly of claim 1 wherein a second end of said cross pin retainer isat least partially positioned within said first aperture when said crosspin retainer is located in its partially-inserted position.
 3. Thedifferential gear assembly of claim 2 wherein said second end of saidcross pin retainer engages a wall defining one of said first and saidsecond apertures to restrict removal of said cross pin retainer whensaid cross pin retainer is located in its fully-inserted position. 4.The differential gear assembly of claim 2 wherein said second end ofsaid cross pin is bifurcated to allow said second end to be insertedwithin said bore extending through said differential housing.
 5. Thedifferential assembly of claim 2 wherein said first end of said crosspin retainer includes face surfaces adapted to allow said cross pinretainer to be grasped and positioned.
 6. The differential assembly ofclaim 2 wherein said cross pin retainer further includes a body having acavity to allow said second end to temporarily collapse when positionedwithin said bore extending through said differential housing.
 7. Thedifferential assembly of claim 6 wherein said body resiliently returnsto an undeformed shape when said cross pin retainer is in itsfully-inserted position.
 8. The differential assembly of claim 1 whereinsaid cross pin retainer further includes a body having a plurality ofradially, outwardly projecting fins adapted to elastically deform toallow said cross pin retainer to be positioned within said housing whensaid cross pin retainer is in its partially-inserted position and toexpand to engage a wall defining one of said first and said secondapertures in said housing when said cross pin retainer is positioned inits fully-inserted position.
 9. The differential gear assembly of claim1 wherein said cross pin retainer includes a support member positionablewithin a longitudinally extending throughbore in said cross pinretainer, and wherein said support member extends from said first end toa second end of said cross pin retainer.
 10. The differential gearassembly of claim 9 wherein said support member extends through saidcross pin retainer and engages a blind bore in said differential housingwhen positioned in its fully-inserted position, said blind bore being incommunication with said first aperture.
 11. The differential gearassembly of claim 1, wherein said differential housing includes surfacesrestricting rotation of said first end of said cross pin retainer fromsaid second rotational orientation to said first rotational orientationwhen said cross pin retainer is in its full-inserted position.
 12. Amethod of assembling a differential gear assembly, comprising: providinga differential housing having a first aperture and a bore; positioning apair of side gears in meshing engagement with a pair of pinion gearswithin said differential housing; positioning a cross pin within saidfirst aperture to rotatably support said pinion gears within saiddifferential housing; aligning a cross bore extending through said crosspin with said bore in said differential housing; positioning a first endof a cross pin retainer at a first rotational orientation andtranslating said retainer within the bore in said differential housingto a partially-inserted position with respect to said differentialhousing, wherein said first end engages a first wall surface of saiddifferential housing and a second end of said cross pin retainer extendsinto said cross bore of said cross pin, said first wall surface of saiddifferential housing restricting further translation of said cross pinretainer when said first end is in its first rotational orientation; andpositioning said first end of said cross pin retainer at a secondrotational orientation and translating said cross pin retainer to afully-inserted position with respect to said differential housing,wherein said first end of said cross pin retainer engages a second wallsurface of said differential housing and said second end of said crosspin retainer engages a wall of said first aperture to restrict removalof said cross pin retainer.
 13. The method of claim 12 furthercomprising positioning a support member in a throughbore within saidcross pin retainer, wherein said support member extends at least fromsaid first end to said second end when cross pin retainer is in itsfully-inserted position.
 14. The method of claim 13 further comprisingpositioning a distal end of said support member within a blind bore insaid differential housing.
 15. The method of claim 12 whereinpositioning said cross pin retainer at said fully-inserted positionincludes positioning said first end of said cross pin retainer betweensurfaces of said differential housing.
 16. The method of claim 15wherein said surfaces of said differential housing restrict said firstend from rotating from said second rotational orientation to said firstrotational orientation when said cross pin retainer is in itsfully-inserted position.
 17. The method of claim 12 further comprisingpositioning a support member within a bore extending through a body ofsaid cross pin retainer at a first position, maintaining said supportmember at said first position while said body is translated from saidpartially installed position to said fully-inserted position, andsubsequently further extending said support member into said body to asecond position.
 18. The method of claim 17 wherein said support memberoccupies a slot formed in said body when at said second position.